Trump didn't know the difference between HPV and HIV, Bill Gates says

What do a couple billionaires talk about when they meet? In the case of President Trump and Microsoft founder Bill Gates, it turns out they talk about sexually transmitted diseases.

In a video obtained by MSNBC, Gates revealed that on two occasions he met with Trump after the election, once at Trump Tower in December 2016 and then in March 2017 at the White House, Trump asked him if human immune deficiency virus and human papillomavirus were the same thing.

"Both times he wanted to know if there was a difference between HIV and HPV. So, I was able to explain that those are rarely confused with each other," Gates told the audience that began to roll with laughter.

Gates was speaking during a meeting of the Bill and Melinda Gates Foundation staff earlier this week, according to MSNBC host Chris Hayes.

Gates also described a time he saw Trump speaking with his 22-year-old daughter, Jennifer Gates.

"And then, like 20 minutes later, he flew in in a helicopter to the same place. So, clearly he had been driven away, but he wanted to make a grand entrance in a helicopter," Gates said.

"When I first talked to him, it was actually kind of scary how much he knew about my daughter's appearance," Gates said. "Melinda didn't like that too well."

Gates said when he met with Trump the newly elected president asked him if vaccines were a "bad thing" and that Trump told him he was exploring forming a commission to look into "ill effects of vaccines."

"I said, 'No, that's a dead end. That would be a bad thing. Don't do that," Gates said.

According to the Centers for Disease Control and Prevention, HIV is an entirely different virus from HPV. It is the most common STD, infecting 79 million Americans. In most cases, people with HPV do not have health problems, but it can cause genital warts and cancer.

Top 20 wealthiest people in the world

No. 2: Bill Gates | Net worth: $90.7 billion | Microsoft co-founder Bill Gates held the title of the world’s richest person since May 2013. Gates remains connected to Microsoft, but he devotes much of his time to philanthropy through the Bill & Melinda Gates Foundation, one of the largest private charities in the world.

Jeff Bezos unseated Bill Gates as the richest person in the world when the markets opened on July 27. Amazon stocks rose more than 1%, driving Bezos’ net worth to $90.9 billion. The founder of Amazon skyrocketed from number five to number one on the list of the world’s wealthiest people in just one year. Outside of Amazon, Bezos purchased the “Washington Post” and created an aerospace company called Blue Origin. Swipe through the gallery to see the world’s richest people, based on Bloomberg’s Billionaires Index.

No. 4: Warren Buffett | Net worth: $74.5 billion | Once dubbed the “Oracle of Omaha,” Buffett is one of the most successful investors. He is the chairman of Berkshire Hathaway, which owns major companies like Dairy Queen, Duracell, and Geico.

No. 5: Mark Zuckerberg | Net worth: $70.5 billion | The 33-year-old Facebook CEO is the youngest billionaire on this list. A Harvard dropout, Zuckerberg co-founded Facebook when he was 19. The popular social media website boasts about 2 billion monthly users.

No. 7: Larry Ellison | Net worth: $52.9 billion | Ellison, left, made his fortune through the software firm Oracle, which he co-founded in 1977. He stepped down as Oracle’s CEO, but remained with the company as chairman and chief technology officer. In addition to his philanthropy, he’s involved in yacht racing with Oracle Team USA.

Oracle CEO Safra Catz speaks during a meeting with President-elect Donald Trump and technology industry leaders at Trump Tower in New York.

No. 10: Charles Koch | Net worth: $47.5 billion | Koch is chairman and CEO Koch Industries, the second largest private company in America. Charles and his brother David split controlling interest in the company, which was created by their father as an oil refinery in 1940. The conglomerate gleans $100 billion in revenue from selling products like Dixie cups and Brawny paper towels as well as oil refining.

Philanthropist David H. Koch attends the U.S. Olympic And Paralympic Foundation Event Hosted By Ellen and Daniel Crown on May 17, 2017, in New York.

Google co-founder Sergey Brin, seen here at a World Economic Forum session in January, wants to build a $100 million blimp, according to the Guardian.

Sweden's IKEA-founder Ingvar Kamprad delivers his speech after he was awarded with the Global Economy Prize 2007 of the "Kiel Institute for the World Economy" in Kiel, Germany, on June 17, 2007.

Chinese business magnate, founder and executive chairman of the e-commerce Alibaba Group, Jack Ma applauds as he attends an entrepreneurship discussion in Nairobi, Kenya on July 20, 2017. Ma, a Special Adviser to the United Nations Conference on Trade and Development (UNCTAD) for Youth Entrepreneurship and Small Business, is on a two-day visit to discuss entrepreneurship, e-commerce and China-Africa trade and business opportunities.

Wal-Mart chairman Rob Walton displays a hat once worn by company founder Sam Walton at the company shareholder meeting in Fayetteville, Ark. on June 5, 2015.

Jim Walton, left, and Alice Walton, right, children of the late Walmart Stores Inc founder Sam Walton, speak during the Walmart shareholders' meeting in Fayetteville, Ark., Friday, June 1, 2012.

Mukesh Ambani, Chairman and Managing Director of Reliance Industries Limited speaks during a joint press conference with British Petroleum (BP) Group Chief Executive Bob Dudley (unseen) in New Delhi, India, on June 15, 2017. According to a news report, Reliance Industries Limited and British Petroleum (BP) will invest 6 billion dollars in India's energy sector.

Jacqueline Badger Mars, executive and part-owner of Mars Inc., stands for a photograph at the National Museum of Women in the Arts 25th Anniversary Gala which she co-chaired in Washington, D.C., U.S., on Friday, April 27, 2012. Mars Inc. manufactures food, snacks, pet foods and beverages.

01/19

No. 2: Bill Gates | Net worth: $90.7 billion | Microsoft co-founder Bill Gates held the title of the world’s richest person since May 2013. Gates remains connected to Microsoft, but he devotes much of his time to philanthropy through the Bill & Melinda Gates Foundation, one of the largest private charities in the world.

02/19

Jeff Bezos unseated Bill Gates as the richest person in the world when the markets opened on July 27. Amazon stocks rose more than 1%, driving Bezos’ net worth to $90.9 billion. The founder of Amazon skyrocketed from number five to number one on the list of the world’s wealthiest people in just one year. Outside of Amazon, Bezos purchased the “Washington Post” and created an aerospace company called Blue Origin. Swipe through the gallery to see the world’s richest people, based on Bloomberg’s Billionaires Index.

No. 4: Warren Buffett | Net worth: $74.5 billion | Once dubbed the “Oracle of Omaha,” Buffett is one of the most successful investors. He is the chairman of Berkshire Hathaway, which owns major companies like Dairy Queen, Duracell, and Geico.

05/19

No. 5: Mark Zuckerberg | Net worth: $70.5 billion | The 33-year-old Facebook CEO is the youngest billionaire on this list. A Harvard dropout, Zuckerberg co-founded Facebook when he was 19. The popular social media website boasts about 2 billion monthly users.

No. 7: Larry Ellison | Net worth: $52.9 billion | Ellison, left, made his fortune through the software firm Oracle, which he co-founded in 1977. He stepped down as Oracle’s CEO, but remained with the company as chairman and chief technology officer. In addition to his philanthropy, he’s involved in yacht racing with Oracle Team USA.

Oracle CEO Safra Catz speaks during a meeting with President-elect Donald Trump and technology industry leaders at Trump Tower in New York.

10/19

No. 10: Charles Koch | Net worth: $47.5 billion | Koch is chairman and CEO Koch Industries, the second largest private company in America. Charles and his brother David split controlling interest in the company, which was created by their father as an oil refinery in 1940. The conglomerate gleans $100 billion in revenue from selling products like Dixie cups and Brawny paper towels as well as oil refining.

11/19

Philanthropist David H. Koch attends the U.S. Olympic And Paralympic Foundation Event Hosted By Ellen and Daniel Crown on May 17, 2017, in New York.

12/19

Google co-founder Sergey Brin, seen here at a World Economic Forum session in January, wants to build a $100 million blimp, according to the Guardian.

13/19

Sweden's IKEA-founder Ingvar Kamprad delivers his speech after he was awarded with the Global Economy Prize 2007 of the "Kiel Institute for the World Economy" in Kiel, Germany, on June 17, 2007.

14/19

Chinese business magnate, founder and executive chairman of the e-commerce Alibaba Group, Jack Ma applauds as he attends an entrepreneurship discussion in Nairobi, Kenya on July 20, 2017. Ma, a Special Adviser to the United Nations Conference on Trade and Development (UNCTAD) for Youth Entrepreneurship and Small Business, is on a two-day visit to discuss entrepreneurship, e-commerce and China-Africa trade and business opportunities.

Wal-Mart chairman Rob Walton displays a hat once worn by company founder Sam Walton at the company shareholder meeting in Fayetteville, Ark. on June 5, 2015.

17/19

Jim Walton, left, and Alice Walton, right, children of the late Walmart Stores Inc founder Sam Walton, speak during the Walmart shareholders' meeting in Fayetteville, Ark., Friday, June 1, 2012.

18/19

Mukesh Ambani, Chairman and Managing Director of Reliance Industries Limited speaks during a joint press conference with British Petroleum (BP) Group Chief Executive Bob Dudley (unseen) in New Delhi, India, on June 15, 2017. According to a news report, Reliance Industries Limited and British Petroleum (BP) will invest 6 billion dollars in India's energy sector.

19/19

Jacqueline Badger Mars, executive and part-owner of Mars Inc., stands for a photograph at the National Museum of Women in the Arts 25th Anniversary Gala which she co-chaired in Washington, D.C., U.S., on Friday, April 27, 2012. Mars Inc. manufactures food, snacks, pet foods and beverages.